Electronic vibrato device with plural manuals



N 1966 J. R. BRAND ET AL 3,286,013

ELECTRONIC VIBRATO DEVICE WITH PLURAL MANUALS Filed June 17, 1963 @eaem/on Tr gger For/0am" Clam/.19. 392mm,.

flenaaey cf. MUM/(Err;

INVENTOR.

United States Patent 3,286,013 ELECTRONIC VIBRATO DEVICE WITH PLURAL MANUALS John R. Brand, Northridge, and Bradley J. Plunkett, Van

Nuys, Calif., assignors, by mesne assignments, to Warwick Electronics Inc., Chicago, 111., a corporation of Delaware Filed June 17, 1963, Ser. No. 288,270

Claims. (Cl. 84-1.25)

This invention relates in general to electronic musical instruments, and specifically to apparatus for adding and controlling vibrato to electrically createdtones.

Vibrato is generally accepted to be a pit-ch or frequency modulation of a musicaltone. Vibrato can be applied by the musician to many musical instruments. For example, the violinist obtains vibrato by rocking ,the

hand which supports the neck of. the violin, thus causing the tip of the finger of this hand to roll up and down the string being pressed by that finger. This alternately increases and decreases the active length of the string,

thus causing the frequency or pitch to become lower and higher respectively. In his most artistic expression, the violinist will frequently tune the string to the desired pitch by depressing it at a ,selected point with the tip of the finger and then add the vibrato gradually by rocking t inactive, and when energize-d begins slowly to apply its effect to the various tone generators vof the organ. The switching means employed to begin the operation of the vibrato device operates responsively to the pressing of a keyboard key and connects the tone generator tothe output of the organ. Hence, a sound is heard immediately without vibrato effect. The vibrato effect is evident if the key is held long enough for the vibrato device to become effective. By this apparatus, if only one vibrato generator is employed, and at least one key is held engaged at all times, the full vibrato effect will be heard on all keys as they are played. 'Ihis is'not the desired effect in most instances and hence the organist is required to allow all of the keys to break contact for a moment in order to stop the vibrato generator.

It is an object of this invention to provide a delayed vibrato system whereby a group of keys are related in such manner that at any time one key is pressed, regardless of the position of the other keys in the group, the vibrato effect is momentarily nullified and permitted to rebuild again. 'Ilhus, there is never a time when a key will express a vibrato effect immediately at the beginning of its play. It is to be understood, of course, that any organ may have other keys which do not have the ability to nullify the vibrato effect, and hence the tones related to such keys will be affected immediately upon expression with a full vibrato effect.

It is another object of this invention to provide a delayed vibrato system for an electronic orga containing two or more keyboard manuals and a single tone generator system which provides tone sources for keys of all manuals, and in which only one of the keyboards operates the delayed vibrato system, wherein the vibrato is applied to the tone generator system at all times except fort-he period immediately following the depression of a key on the keyboard controlling the delayed vibrato system, so that sound with full and normal vibrato is available at all times when playing keys on any keyboard other than the one which controls the delayed vibrato system.

- This invention issaid to relate to delayed vibrato, and hence it is an object of this invention to provide an improved delayed vibrato control and effect. Vibrato which can be heard as soon as a key ispressed is well known in the electric and electronic instrument art. However, this invention will provide delayed vibrato which is available to each key separately, but which will not express the vibrato effect under any circumstances until the key has been held i the switch contact position for a specifiedperiod of time.

Also, in the type of apparatus in the prior art, wherein the vibrato effect is a matter of gradually activating the vibrato generator, many pieces of apparatus are required. many in fact, that if each note were to be separately supplied with vibrato means, it would make a bulky and expensive instrument. Hence, reliance upon mathematical probability is used in order to enable a fewer number of vibrato devices to be applied to a plurality of tone generators. I

It is one of the principal objects of the present invention to enable v.the creation .of delayed vibrato effect with minimum equipment. i

It is a further object of this invention to enable a key which is subject to delayed vibrato effect to be played for a short duuation without creatingthe vibrato effect, but to bring-forth the vibrato effect upon "holding the key.

It is 811111 a further object of this invention to enable the instantaneous cancellation of vibrato effect by lifting and then reactivating a given key.

In accordance with these and other objects which will become apparent hereinafter, a preferred form of the present invention is disclosed in the accompanying drawings in which:

- FIGURE 1 is a schematic illustration of a system which embodies the principles of the present invention;

FIGURE 2 is an illustration setting forth the creation of an electrical impulse used to trigger the vibrato control apparatus of this invention.

FIGURE 3 is an illustration of the relationship between the creation of signals shown in FIGURE 2, and the envelope which is developed about a vibrato generator output in accordance with the principles of this invention.

FIGURE 4 is a diagram of a circuit which is responsive -to a trigger signal, such as shown in FIGURE 2, to create the envelope of FIGURE 3.

FIGURE 1 is a.simplified schematic illustration of the general system in which this invention is applicable. The reference number 10 indicates a single tone generator, representative of the greater number of tone generators which are required for an actual electronic instrument.

In an instrument environment, the tone generator is employed by closing of a switch to allow the signal generated to be conducted out to other parts of the instrument and eventually to an audio system. In the diagrammatic system of FIGURE 1, the circuitry is from the tone generator 10 to and through two keyboards 11 and 12. The keyboards 11 and 12 have many individual keys operating such switches suggestive of the manuals of a two manual organ. The one tone generator in this illustration will be expressed only by the key of that one particular tone. Nevertheless, the illustration is suflicient with the understanding that the balance of the keys will each be supplied by other like tone generators.

The tone is expressed from the generator 10 by pressing a particular key, and is thus connected into a circuit feeding to a formant and voice system 13 as illustrated. From the system 13, the tone is rendered audible by an system represented by thespeakerlS.

Tone generators normally produce a constant frequency which may be represented on a graph in periodically reoccurring Wave form. According to the particular type of tone generated, thewave form may be pure sine, saw tooth, square, or other wave form, butnonethelessis of constant frequency and amplitude. Hence, if expressed without alteration, itwill produce a conventional tone Without Vibrato.

A vibrato generator typically is capable of modulating the output of a tone generator by superimposing its own wave form upon the generator. That is, the vibrato generator creates an output waveform which has the. effect of altering the output of=the tone generator;

According to-the prior art, sucha vibrato generator, is employed but allowedto remain inactive until a key of the keyboard is moved to connect a tone generator to the output of the organ. The vibrato generator begins tO'OP- erate, building up slowly in order thatits effect is not immediate, butrather builds up within a period of time. Hence, if a key of this prior device is held until the vibrato effect is experienced and thenanother key employed, prior audio to releasing the first key, the tone from-the tone generator connected through the second key will be: in full vibrato effect as soon as it is brought into operation. To avoid such defeat of the intended purpose, a plurality of. vibrato generators are employed and connected according to laws of probability. Thus, a complex system is needed wherein several vibrato generators are used. u a i a The present invention makes possible the use of a single vibrato generator,.as well asproducing the other novel effects previously referred to. The vibrato generator is connected to-all of the tone generators of the instrument. It is in operation at all times that the vibrato feature of the organ is in use. Hence, the vibrato modulation effect is delivered to all tone generators, and if a tone generator is connected to the output of the organ, it will be heard in full vibrato. This invention permits delayed vibrato by enabling some of the keys, at least, to operate a control system which momentarily cancels the effect of the vibrato generator and then allows the effect fromthe vibrato. generator to buildup to its normal full value. The operation of a key, therefore, connects the tone generatorto the output of the organ for'expression of a conventional tone without vibrato by simultaneously nullifying the effect of the vibrato generator when the tone generator is connected by the key to the output of the organ. This effect is graphically illustrated in FIGURE 3 of the drawing. The wave form is intended to depict the output wave form of a vibrato generator. The envelope around the 'wave form is created by the'control apparatus which will be explained hereinafter.

The vibrato generator is illustrated in the circuit of FIGURE 1, and referred to be reference number 17, in order for the modulating effect of the generator 17 tobe effective upon the tone generator, it must conduct through the wires 18 and 19 into the tone generator. Hence, the generator 17 is rendered effective by means of an. on-off short circuiting switch 21. Also,the intensity of vibrato effect may be controlled by a variable resistor 23 which is used to attenuate the vibrato signal and hence provide a depth control. resistor 23 is permitted, the effect will be null and generator 17 will have full effect. As the value of resistor 23 is decreased, the effect of the generator 17 upon generator 10 will be decreased. Thus, it will be seen that the effect of generator 17 is controlled by attenuation of its output. A light dependent resistor is employed in this invention in such a manner that vibrato depth is a function of light falling on the surface of the resistor. The circuit in the drawing is shown with a light dependent resistor 25 used as a shunt element. However, it may be used as a series element as well. For purposes of this invention,

Thus, if the full resistance of the control URE 1 by a block-labeled trigger."

the shunt circuit is used. In this case, the light dependent resistor '25 has a'high resistance value until such time as it is exposed to light. Hence, the resistor will normally have no particular shunting effect, and hence, will not affect the output of the generator 17. Exposure of this resistance to light will cause a rapid shunting effect and thus essentially eliminate the effect of the generator 17. However, the characteristic of the resistor 25 is such that after reduction of the resistive effect thereof, and after darkness is restored, it begins to recover at a predetermined rate according to the design of the resistor. Hence, the effect of the generator 17 is removed rapidly, but then begins at once to build up.

Thus, it is feasible, according to this invention, to have an electrical musical instrument utilizing an electrical tone generatorwith selective means in the form of switches operated by the organ keys for controlling 'the output of impulses by the tone generator, wherein a vibrato device is constantly operative to affect the tone generator, and

having means operative only upon operation of the controlling means forinullifying .lthe effect of .the vibrato device upon the tone generator momentarily but permitting "by :the'use' of a trigger mechanism which is operative upon actuation era key to cause a light to flash in the vicinity of theiligh t dependent resistor 25.

It is known in electrical musical circuitry art to provide a trigger. pulse operable on actuation of a key, to producepe-rcussiveeffects. The function required from sucha trigger-circuitry, to serve the purposes of this invention, is that each time a key is pressed, a pulse signal will be "available to control the subsequent apparatus needed for delayed vibrato .contro. Although prior art provides apparatus which could be employed to produce a trigger pulse once the requirements of the present invention are understood, a specific apparatus, well designed for the purposes of this invention, may be drawn from the teaching shown in :the co-pending application Cutler et al., Serial No. 249,306 filed January 2, 196-3., Patent No. 3,235,650. In this teaching, there is shown a percussion circuit for a musical instrument such as an organ, wherein a plurality of tone generators are employed. This teaching sets forth the use of a plunality of individual capacitors corresponding respectively to the keys, convert in such a manner so as to produce the required trigger pulse whenever a key is pressed, irrespective of the operative condition of any other-key. This apparatus produces one pulse only upon pressing the key, and does not produce .a pulse upon release of the key.

This pulse producing equipment is indicated in FIG- In FIGURE .2, the diagram'is shown to represent the output of a trigger pulse from such apparatus. In FIGURE 2, a section of a keyboard is illustrated and 'a lead 'line 26 from the keyboard extends to a chant and the chart is representative of a voltage line 27. Note that the line 27 is perfectly uniform except for a pulse curve 28. Pulse curve 2 8 represents the pulse produced at the instant 'of pressing a given key of the keyboard. This pulse curve 28 will be repeated each time a key is pressed.

Refer to the FIGURE 4, which is a circuit diagram of the device responsive to the trigger pulse and located in the FIGURE 1 within the block diagram 29. The circuit shown in this FIGURE 4 is a two-stage current mode amplifier which is used to control the duration of operation of light bulb 33. The circuit is activated each time a key is pressed on the keyboard of the organ. This circuit includes transistors TR1 and TRZ, both biased so that they are normally cutoff. Upon pressing a key, the positive going pulse 28 is applied to the point 31 on the circuit drawing, FIGURE 4. v p e The pulse 28 drives the transistor TR1 into conduction, charging a condenser C1 in a direction of polarity which biases TR2 through resistor R5 into saturation. The bulb 33 which is used to illuminate the light dependent resistor 25 is in the collector circuit of TR2 and is energized by the resulting collector current flow in TR2 as shown at 203. On termination of the input pulse 28, the capacitor C1 discharge-s toward its steady state value through the base circuit of TR2, and the series combination of resistors R3 and R4, as shown at 202. The result is the turning off of TR2 after a time delay, as shown at 204, and as a consequence, the light bulb 33 goes off. If a key of the organ is pressed during the above described cycle of operation, the cycle will be reinstituted from the beginning. In this way, the light'is held on during periods whenever keys are played for a short duration, but allowed to go out when notes are sustained.

An intrinsic important property of the light dependent resistor used in this application'is its resistance vs time characteristic. 'Upon application of light, the resistance drops immediately. Upon removal of the light, the resistance rises roughly exponentially toward its dark value at a rate controllable in the manufacture of the resistor. The resistance vs time relationship of the device is used in this application to control the rate of vibrato amplitnde build-up. The period of time of full illumination of bulb 33 represented by the plateau top at 206, results from the fact that the transistor TR2 is rendered conductive for a period of time longer than normally would be available 'by the mere introduction of the control pulse 28 from the percussive circuit. I

Light is directed'from bulb 33 on the light dependent resistor 25 causing its normally high resistance to drop to a very low value. Since the light dependent resistor is in a circuit which will shunt the output of generator 17, the drop of resistance causes a substantially complete attenuation of the output of generator 17 and an accompanying nullification of the effect of the generator. Thus, the moment a key is pressed, the effectiveness of the generator 17 is canceled. The cancellation effect is shown in the FIGURE 3. In FIGURE 3, a time-voltage chart, two pulse curves 28 are illustrated, one being in full lines and the other in dotted lines. The dotted line curve represents a second pulse position in the future following the initial pulse 28. Note the instantaneous drop to zero of the curve enveloping the vibrato generator output wave form. Thus, the pressing of a key brings forth first a generated wave form without vibrato modulation, but the inherent characteristics of the light dependent re'sistor 25 allows the output of generator 17 to recover in a predetermined curve as shown in FIGURE 3. Hence, if the key is held until the recovery effect can become noticeable, the effect of vibrato upon the tone will begin.

The dotted outline of the pulse following the full line pulse illustrates the effect of pressing that same key a second time, or pressing another key have the trigger circuitry. Thus, if either of these two conditions obtain, then a new pulse is created from the trigger circuit, and the vibrato voltage is brought once more to zero condition and the vibrato effect is canceled. Thus, the musician may play on the manual having this delayed vibrato effect, and yet experience no vibrato in the output of the organ if keys are used in sufficiently rapid order. However, the musician is able, as he plays a musical score, to hold or to linger on one or more keys and bring forth this vibrato effect Whenever he desires.

Furthermore, as illustrated in FIGURE 1, the lower manual is not equipped with circuitry which produces the trigger pulses 28. Hence, that manual may be played alone in its normal manner without any effect upon the production of vibrato and therefore, if the vibrato generator is operative, all notes expressed from the lower keyboard will have vibrato.

Electronic organs of the two manual type frequently use a common tone generating system for both manuals.

This obviously is desirable from an economic standpoint. Inasmuch as vibrato is usually obtained by frequency modulating the tone generator oscillators, it is obvious that the tones from either keyboard will have no vibrato, or will have vibrato, depending upon the state of vibrato selection made by the organist. In organs of this type, using delayed vibrato created by prior art, no vibrato will be heard when playing keys on the keyboard which does not control the delayed vibrato system. One of the accomplishments of the present delay vibrato invention is the ability to have delayed vibrato on one manual which can be played rapidly enough so that no vibrato is heard, and full vibrato on the other keyboard by simply transferring one or both hands to the other manual and not simultaneously playing on the manual which controls the delayed vibrato effect.

' 'As previously indicated,'vibrato is generally accepted to be a variation in frequency or pitch of a musical tone which occurs at a regularly re-occurring rate. Typically, this rate is six or seven cycles per second. Tremolo is generally accepted to be an amplitude modulation of a musical tone re-occurring at the same rateas vibrato. There has been some tendency in the literature and art to use the terms vibrato and tremolo interchangeably and, indeed, in some cases effects are created which are combinations of the generally accepted definitions of vibrato and tremolo. Iit is understood and recognized that the delayed vibrato system of the present invention operates and applies equally well to systems creating frequency'or phase modulation, amplitude modulation, or combinations of these.

While the instant invention has been shown and described herein in what is conceived to be the most practi cal and preferred embodiments, it is recognized that departures may be made therefrom within the scope of the invention which is therefore not to be limited to the details disclosed herein but is to be afforded the full scope of the claims.

What is claimed is:

1. In an electrical musical instrument utilizing a tone generator and a playing key pressable for causing the output of the tone generator to be effective upon an audio system;

a vibrato oscillator connected to provide'a constant vibrato effect upon said tone generator;

modifying means for rendering said effect null followed by a gradual restoration of full vibrato effect; and

control means operable by pressing said key for initiating operation of said modifying means.

2. In an electrical musical instrument utilizing a tone generator and a playing key pressable for causing the output of the tone generator to be effective upon an audio system;

a vibrato oscillator connected by a circuit to provide a constant vibrato effect upon said tone generator;

a variable resistance means in said circuit for rendering said effect null followed by a gradual restoration of full vibrato effect; and

control means operable by pressing said key for rendering said resistance means fully operative to nullify said effect and thereafter restore the original condition to thereby gradually restore said effect.

3. In the instrument defined in claim 2;

said resistance means being a relatively high value resistance in shunt circuit, and adapted to become substantially less resistive followed by a gradual return to said relatively high value resistance.

4. In the instrument defined in claim 2;

said resistance means being a relatively low value resistance in series circuit, and adapted to become substantially more resistive followed by a gradual return to said relatively-low value resistance.

5. In an electrical musical instrument utilizing a tone generator and a playing key pressable for causing the output of thetone generator to be effective upon an audio system;

a vibrato generator connected to said tone generator by a transmission circuit adapted to provide a constant vibrato effect uponsaid tone generator;

said vibrato generator being reducible in effectiveness upon the tone generator by blocking the transmission of the output from said vibrato generator to said tone generator;

key responsive means for providing said reduction in effectiveness of said vibrato generator upon the press ing of said key;

whereby, said vibrato generator is nullified as the key first expresses a tone fromsaid tone generator.

6. In an electronic organ having a tone generator, and

an audio system for expressing tones generated;

a keyswitch toconnect said generator into said audio system;

a vibrato generator connected by a vibrato circuit to said tone generator, said vibrato genera-tor being in constant operation andacting to apply vibrato modulation to the tone generated;

said vibrato generator being reducible in effectiveness upon the tone generator by blocking thev transmission of the output from said vibrato generator to said 7 tone generator;

blocking means responsive to light; 1

1 a trigger pulse generator means responsive to operation ofsaid key for producing controlstimulus;

a light producing circuit operative responsively to said control stimulus, said circuit comprising a first transistor capable of conducting .upon having saidcontrol stimulus applied to the base thereof, a second transiss tor controlled by said first transistor to conduct while the first-transistor is conducting, a holding circuit cans:

- ing said second transistor to conduct for a period of time longer than the period of the trigger pulse, and a light emitting device in a circuit including said second transistor as a switch to emit light during the period said second transistor is conductive,said light being, effective upon said blocking means.

7. In an electronic organ;

a tone generator and audio system;

a key switch to connect said generator into said system;

a vibrato generator connected by a circuit to said tone generator, said vibrato generator being in constant operation to supply vibrato modulation;

a light dependent resistor shunting said circuit, said light dependent resistor characterized by a normal high resistance of a value to render said shunt ineffective, and being heavily conductive upon exposure to light to thereby render said shunt circuit effective, and regaining resistive value gradually after being conductive;

a trigger pulse generator means responsive to operation of said key switch for producing a pulse signal;

a light producing circuit operated responsively to said trigger pulse, said circuit comprising a first transistor capable of conducting upon having said pulse applied to the base thereof, a second transistor controlled by said first transistor to conduct while the first transistor is conducting, a holding circuit charged during operating of said first. transistor causing said second transistor to conduct for a period of time longer than the period of the pulse, and a light ,emitting device in a circuit including said second transistor as a switch to emit 'light during'the'period said second transistor is conductive, said light being effective upon said light dependent resistor;

whereby, the vibrato effect upon the tone generator will be nullified momentarily, allowing a normal tone to be expressed, followed by gradual modulation if the key is held. v 1

8. An electric organ having two key manuals, a plurality oftone generators, aplur'ality of playing keys in each manual, each key operable for causing at least one tone generator to be effective;

, a vibrato oscillator circuit connected to, at least some of said tone generators, said circuit being nullifiable to any selected degreeby shunting said'circuit to a selected degree; I

a light dependent resistor in ashunt circuit of said vibrato oscillator circuit, saidlight dependent resistor having a very high resistance until exposed to light; means operable by'operation of a key of one only of said manuals to expose said light dependent resistor to a momentary light flash; J j

"' whereby vibrato willbe delayed when tones are instituted on one manual, but not delayed when tones are instituted on the other manual. I I

9. Instrument in accord-ance with claim 2,w herein said variable resistance meansicomprises light-dependent re- 'sistance means, and f l said control means comprises light means for applying a pulse of light to said light-dependent resistance means upon pressing of said key.

10'. An electrical musical instrument in accordance with claim 5, including in addition:

circuit means for restoring effectiveness of said vibrato generator, following the reduction thereof by said key responsive means,

whereby after said reduction, said effectiveness is automatically restored.

References Cited by the Examiner UNITED STATES PATENTS 2,768,551 10/1956 Chick 841.25 2,899,644 8/1959 Leslie 841.25 2,928,306 3/1960 Hanert et al. 841.25 3,045,522 7/1962 Markowitz et al 84-125 ARTHUR GAUSS, Primary Examiner.

J. BUSCH, Assistant Examiner. 

1. IN AN ELECTRICAL MUSICAL INSTRUMENT UTILIZING A TONE GENERATOR AND A PLAYING KEY PRESSABLE FOR CAUSING THE OUTPUT OF THE TONE GENERATOR TO BE EFFECTIVE UPON AN AUIDO SYSTEM; A VIBRATO OSCILLATOR CONNECTED TO PROVIDE A CONSTANT VIBRATO EFFECT UPON SAID TONE GENERATOR; MODIFYING MEANS FOR RENDERING SAID EFFECT NULL FOLLOWED BY A GRADUAL RESTORATION OF FULL VIBRATO EFFECT; AND CONTROL MEANS OPERABLE BY PRESSING SAID KEY FOR INITIATING OPERATION OF SAID MODIFYING MEANS. 